Several methods of tubal patency assessment have been previously used. These include hysterosalpingogram, chromopertubation, chlamydia antibody testing, and sonosalpingography. In a hysterosalpingogram, an X-ray dye study of the Fallopian tubes is performed. Chromopertubation is performed during laparotomy or laparoscopy, both of which are abdominal surgeries. Chlamydia antibody testing is a blood test reflecting risk for tubal disease from previous chlamydia infection. Sonosalpingography is an approach that uses ultrasound to observe infusion through a transcervical catheter of a combination of air bubbles in saline or other combinations of fluids with or without air to evaluate the Fallopian tubes. Hysteroscopy has also been used to advance a catheter into the Fallopian tube, with infusion of dye through the catheter. A hysteroscope can also been introduced into the uterus and then after removal of the hysteroscope be followed by ultrasound to see if fluid accumulated in the pelvis during the hysteroscopy without directly observing the process of air or fluid entering or traversing the Fallopian tubes. Falloposcopy has also been used where a camera enters the Fallopian tubes.